Elevator



ELEVATOR.

,087. Patented Dec. 1-0, 1889.

Fig. 1.

MT/VESSES.

l. PETEE Photo-lithograph, Waahingon, D. C,

PATENT FFICE.

CHARLES R. PRATT, OF BOSTON, NASSAUITFSETTS.

ELEVATOR.

SPECIFICATION forming part of Letters Patent No. 417,087, dated December 10, 1889.

Application filed April 16, 1889. Serial No. 307,407. (No model.)

To all whom it may concern.-

Be it known that 1, CHARLES R= PRATT, of Boston, county of Suffolk, State of Massachusetts, have invented certain new and useful Improvements in Elevators, of which the following is a specification.

The object of my invention is the construction of an elevator especially adapted to be operated by an electric motor and provided with safety devices, hereinafter more fully described, to prevent the cables from slacking should the car stick in descending the hoistway.

In the drawings accompanying and'forming a part hereof, Figure 1 is a side elevation showing an elevator-hoistway, as also my hoisting apparatus at the foot of the hoistway and indicating the means of applying the motor thereto. Fig. 2 is a plan view of the same. Fig. 3 is a perspective view of the cross-head which carries the traveling sheaves and a loosely-mounted nut, and also showing the pawl-and-ratchet mechanism which S61 ves to hold the nut in a fixed position relatively to the cross-head when the cross-head is hoisting, or, if the pawl be thrown out of contact with the ratchet, to free the nut and allow it turn with a screw-shaft. Fig. 4 is a longitudinal vertical section showing the construction of the nuts and pzml-and-ratchet mechanism.

A represents the elevator-hoistway B, the car, which is suspended by means of ropes a from overhead sheaves Z1 c is a counter-balance suspended in the usual manner.

The hoist-ropes a pass down from the overhead sheaves t to the stationary sheaves (Z journaled at one end of the horizontal frame D, which supports and carries the hoisting apparatus. The hoisting-ropes after passing under the stationary sheaves d are carried around the traveling sheaves f and are then anchored at the end at a fixed point near the said stationary sheaves (1 The number of stationary sheaves (1 will he obviously equal to the number of traveling sheaves employed, and that will depend upon the number of times which it is desired to multiply the movement of the traveling sheaves in the movement of the elevator-car, as will be obvious to. those skilled in the art. In the drawings two travelin sheaves are shown for each hoisting-rope.

The side pieces of the frame I), which is set generally for convenience in the base ment of the building near the foot of the hoistway, but which may of course be set in any position desired, are grooved to form ways which receive the ends of the crosshead E, upon which the traveling sheaves are mounted.

For convenience of construction the crosshead E is provided with the horizontal rods g which are bolted to the cross-head and between which the traveling sheaves f are mounted, all as will. be clear to those skilled in the art. The cross-head E is provided with a nut j of cylindrical shape, which is set loosely in the cross-head, and which is flanged, as shown at 72 Fig. 2, the flange 71 being on the inner side of the cross-head E. The nut is threaded interiorly and adapted to receive the screw-shaft 7. which is mounted on bearings, one of said bearings being at P, Fig. 2, and the other at m in the end of the frame D. The forward end of the shaft U, which projects in front of the end of the frame D, is provided with a gear n which meshes with a pinion 19 fast on the motor-shaft 1 Behind the gear a a collar is secured to the shaft k and a buffer 1 having a rubber cushion Z behind it,'is set in the end piece of the frame D. Between the buffer and the collar 1' are placed cone roller-bearings a the proximate surfaces of the collar and the buffer being formed to receive the same. By this device the friction of the shaft 11 resulting from the constant pressure of the load, is reduced. It will be clear that if the shaft 70 be revolved the cross-head E and its sheaves f may be made to travel from end to end of the frame I), and thus raise or lower the elevator-car.

As a safety device, I have constructed a frame 6, (shown in Figs. 2 and 4,) whichI have secured firmly to the flange 71? of the nut. This frame 6 is provided at one end with an aperture to accommodate the shaft: 70*. On the shaft k inside the frame 6, I place a nut (See Fig. 4.) The side of the frame 6 is slotted longitudinally .to receive a block or lug d, which is firmly secured by a screw or in other suitable manner to the periphery of the nut (.Z. The slot in which the block (1' lies is of the same width substantially as the block, but is considerably longer. (See Fig.

By this arrangementthe nut (Z will revolve with the frame 6 and with the nut but is under no strain; and as the threads of the nut j wear, the nut j will approach the nut d, the block (1 moving relatively to its slot. As the nut (Z does no work, its wear will be very slight, and in case the thread of the nutj should break, the nut l would act as a safety and sustain the load. The approach of the nut to the nut (Z shows the wear of the working-nut J and thus a means is afforded whereby, by simple inspection of the machine, the condition of the working-nut is revealed. As will be obvious, the block (Z operates simply as a lug or projection on the nut d; but is made separate therefrom and screwed thereto for convenience in construction. WVhen the cross-head E is lowering, if the car should stick for any reason the friction between the flange 7&2 of the nut 7' and the cross-head E is relieved, and the nut j revolves with the shaft k and the cross-head stops, thus preventing the paying out of the hoisting-cables, even although the motor is not stopped. \Vhen the cross-head reaches the end of its travel in lowering, the frame 6, which is rigidly secured to the nut J comes in contact with a buffer 1', which consists of a metal ring or cylinder set in a socket in the collar (0*, which is fast, by means of a set.- screw h to the shaft 76?. Behind the buffer f in its socket is a rubber cushioning-ring b to prevent shock or jar in stopping the motion of the cross-head. If the speed of the car is not slackened by the operator before it reaches the bottom of the hoistway, the frame ,6 comes in contact with the buffer and the nut j gradually locks with the buffer f and turns with the screw-shaft k thus stopping the travel of the cross-head without shock or jar. Anti-friction washers a and. a rubber buffer 1) are placed between the flange of the nut 3' and the cross-head E. The washers act to reduce the friction between the flange of the n utj and the cross-head where the nut is looked, as above stated, with the buffer f and compelled to turn with the screw, and the rubber buffer Z2 acts to further reduce the shock in the stopping of the cross-head at the end of its lowering travel, and at all times serves to lessen any vibration which may occur in the working of the apparatus, and the rubber cushion lbehind the buffer 29, previously described, accomplishes the same result. hen the cross-head E is hoisting, the nut is positively locked by means of a ratchet h, which is keyed, as shown in Fig. 3, to the nut, and with which the pawl vi, pivoted. at t" to the cross-head, co-operates. \Vhen the cross-head has reached the end of its hoisting-travel, the pawl '2 is freed from its ratchet by the following device: A striker is secured to the cross-head (see Fig. and projects beyond the same toward the end or cross-piece of the frame D, and so as to come in contact as the cross-head approaches the frame, with one end of a bell-crank leverj, which is pivoted at j to lugs on the frame. The other end of said bell-crank lever projects toward the cross-head and under the free end of the pawl As the bell-crank lever is rocked bythe thrust of the striker 70 it raises the free end of the pawl and releases the pawl from contact with the ratchet, thus freeing the nut] and allowing it to turn with the shaft 70 which it will. do when it jams or looks with the collar g, which is fast on the shaft lif (See Fig. 2.) If for any reason the car in descending stops, either midway of the hoistway or at the bottom thereof, as heretofore described, and the screw continues to revolve, as in lowering the car, the pawl and ratchet do not interfere to prevent the shaft 7r? and nut j turning together.

The friction of the flange of the nut j on the cross-head when the cross-head is lowering its load is greater than the friction of the said nut on the screw-shaft, and consequently the nut remains stationary relatively to the cross-head, and the apparatus will lower its load. In addition, it is to be noted that the pitch or angle of the thread of the screw-shaft tends, when the cross-head is lowering, to revolve the nut in a direction opposite to the movement of the screw, and thus to hold the nut stationary relatively to the cross-head.

The electric motor shown at K maybe wired in any well-known manner. In Fig. 1 Ihave shown the wires in dotted lines arranged in connection with a switch in the elevator-car, whereby the motor may be controlled from the car. The automatic clutch device indi cated at L is the subject of another application for Letters Patent No. 295,031, and'will be found fully shown and described therein. The motor operates a sleeve which is loosely mounted on the shaft 1 and which carries the member a of the clutch device. The member 60' has a lateral movement 011 the sleeve, being secured thereon by a spline, and as the weights If fly outwardly under the influence of centrifugal force as the sleeve revolves the toggles c are straightened and the member a of the clutch is forced against the other member (Z thereof. The member (Z is fast to the shaft (1 and this operation of the clutch device causes the shaft g to revolve.

\Vhat I claim is 1. An elevator comprising a car and hoisting-ropes therefor, a traveling cross-head connected with the hoistingropes, a nut mounted in said cross-head, a screw-shaft co-operating with said nut, an actuating-shaft co-operating with said screw-shaft and carrying an electro-motor and automatic clutch device, said motor being controlled by a switch in the elevator-car, substantially as shown and described.

2. A hoisting apparatus consisting of a trav IIO eling cross-head provided with'sheaves for the hoisting-ropes and mounted in a suitable frame, in combination with a nut mounted in said cross-head, and a screw-sl'iaft co-operat ing with said nut, said nut being provided with a flange and having an interposed layer of rubber or similar material between said flange and the crosshead, substantially as shown and described.

3. Ahoisting apparatus consisting of atraveling cross-head prox'ided with sheaves for the hoisting-ropes and mounted in a suitable frame, in combination with a nut mounted in said cross-head, a screw-shaft co-operating with said nut, a frame 6, secured to said nut and inclosing a safety-nut, for the purposes and substantially as shown and described.

1. In a hoisting apparatus, the combination of the traveling cross-head E, the nut 7' mounted therein, the screw-shaft W, the frame 6, fast to said nutj and the nut d 011 said shaft 73, said nut (Z having a block secured thereto and projecting into a slot in the side of the frame 6, whereby the security of the load isincreased and the wear of the working-nut may be easily noted, substantially as set forth.

5. In an elevator hoisting apparatus hav ing a traveling cross-head carrying sheaves for the hoisting-ropes, the combination there with of a nut mounted loosely in said cross head, and a screw-shaft co-operating with said nut, said shaft having a collar secured thereto at each end of the travel of said nut, whereby as the nut reaches the end of its travel in either direction it will jam against the collar and turn with the screw, thus stopping the cross-head, substantially as shown and described.

6. The combination, with the hoisting apparatus consisting of a traveling cross-head, a nut mounted therein, and a screw-shaft cooperating with said nut, of a ratchet fast on said nut, and a pawl arranged to coact there with and pivoted to the cross-head,1t'or the purposes and substantially as shown and described.

7. The combination, with a hoisting apparatus comprising a traveling cross-head and suitable frame therefor, a nut mounted in said cross-head, and a screw-shaftco-operating with said nut, of a ratchet fast to the said nut, a pawl pivoted to the cross-head, a striker k, seeu red to the cross-head, and a bellcrank lever j, pivoted to the frame and arranged when moved by the striker to free the pawl, for the purposes and substantially as shown and described.

8. The combination, in a hoisting apparatus comprising a movable cross-head and suitable frame therefor, a nut mounted in said cross-head, and a screw-shaft co-operating with said nut, of a collar 0* on said shaft,

a buffer i on the frame,a yielding cushion for said buffer, and anti-friction bearings between said buffer and collar, for the purposes and substantially as shown and described.

9. A hoisting apparatus comprising a movable cross-head, a nut mounted loosely therein, and a screw-shaft co-operating with said nut, said nut having a flange inside the crosshead, whereby when the cross-head is carrying its load the friction between the crosshead and said flange is greater than the friction of the nut on its screw-shaft, and when the cross-head is not loaded is lessened and allows the nutto turn with the screw, for the purposes and substantially as shown and described.

CHARLES R. PRATT.

Vitnesses:

WILLIAM A. h/IACLEOD, ROBERT WALLAoE. 

